function second_summand(CONSTS, plot_data)

    c     = CONSTS.c;
    k0    = CONSTS.k0;
    a     = CONSTS.a;
    d     = CONSTS.d;

    zeta = 0.3*d;
    m = 1;
    period = pi/(k0*a);
    dots_per_period = 5000;
    num_periods = 3;
    q_vec = (0.0 : period/dots_per_period : num_periods*period)';

    if (plot_data)
        fprintf('N=%d', size(q_vec, 1));
    end

    y_vec = (2*pi/c*a) * func_2(q_vec, zeta, m, CONSTS);

    if (plot_data)
        figure; plot(q_vec, y_vec); title('func_2');
    end

end